Hi Barb, welcome to TP
Losing the ability to swallow or even speak is common in AZ in the later stages, however, our mouths are always producing saliva which without even thinking about makes us swallow as a regular reflex reaction, sit still for 5 minutes and you'll see what I mean.
People with AZ first forget to swallow but then realise too late so they cough, later on they tend to choke and cough violently as the saliva slips to near to the lungs and the final line of defence kicks in and the body rejects liquid going into the lungs.
Cough remedies are designed to clear fluid from the lungs not stop liquids going in there and some relax the muscles so achieving the reverse of what you want.
Just an opinion, you should seek proper medical advise...but I would suggest it's an early stage of "dysphagia" which if you look up may provide some answers, but I think giving an expectorant which pushes moisture up from the lungs to someone who's having a problem swallowing might make you clear your throat a bit more than normal.
K